In mattress and cushion construction, a need has been recognized for mattresses or cushions which provide comfortable and durable supporting surfaces, but are also cost-effective to produce.
A variety of configurations have been used to provide such optimum sleeping surfaces. Some mattress configurations have included types of foam rubber to provide a cushioning effect to support the human body. Other configurations have utilized a plurality of spaced-apart coil springs, which, depending on the user, provide support preferred to that provided by foam rubber only.
Spring Assemblies
One example of such a spaced-apart coil spring assembly is U.S. Pat. No. 4,051,567 to Hutchinson, which discloses a coil spring assembly including aligned rows of coil springs connected together within each row and between rows, and also includes additional reinforcing springs which are interspersed about the periphery of the spring assembly, with all springs being held in place by border helical and helical tie wires. Although such mattress configurations are effective, disadvantages are apparent in that such linked configurations do not allow for independent action of the springs, thus preventing the mattress from conforming accurately to the user's body.
Pocketed Coil Springs
It has also been known to provide springs in a preloaded state, prior to assembly of the springs into a mattress or cushion construction. The preloaded configuration of the springs provides a supporting structure that is sufficiently yielding to be comfortable but does not deflect excessively as would a cushion or other structure composed of similarly configured but non-preloaded springs.
One example of such construction is in U.S. Pat. No. 1,466,617 to Foster, entitled "COVERED SPRING STRUCTURE", discloses a tubular covering formed on flexible material such as cotton cloth or the like, provided by bringing opposite edges of a long strip of cloth together and sewing through both layers of cloth near the adjacent edges by a row of stitches. The covered springs are assembled side-by-side and then fastened by fastening means such as U-shaped metal clips. The feature of having the springs held under partial compression provides a structure that is sufficiently yielding to be comfortable but without the great extent of sag or give before the person is sustained that is present in a cushion or other structure composed of equally soft or resilient springs. Pocketed Coil Springs
In order to provide improved handling characteristics, it has been known to provide "strings" of pocketed coil springs, wherein the springs are encapsulated in a preloaded state within pockets formed in an elongate strip of fabric, the axes of the springs being generally parallel to each other. For purposes of this application such configurations will be referred to as "pocketed coil strings". It should also be understood that the terms "coil", "spring", or coil spring are interchangeable for purposes of this discussion.
In my U.S. Pat. No. 4,439,977, entitled "METHOD AND APPARATUS FOR MAKING A SERIES OF POCKETED COIL SPRINGS", a method and apparatus are disclosed for making coil springs pocketed within individual pockets in an elongate fabric strip comprised of two overlaying plies capable of being thermally welded together. The fabric strip is fed along a guide path during which compressed springs are inserted between the plies with the axes of the springs substantially normal to the planes of the plies, whereafter the fabric plies are thermally welded together longitudinally and transversely to form a string of pocketed coils. After thermal welding, the pocketed coils are passed through a turner assembly during which the springs are reoriented within the fabric pockets to positions wherein the axes of the springs are transverse to the fabric strip. Although this method of manufacture has several advantages, one disadvantage is that, during the turning process, the springs may tend to become "hooked" on themselves, and do not extent to their proper positions. Therefore, additional and costly labor is required to orient the "hooked" springs to their desired configurations. Even if the springs do not become hooked, difficulties may still arise in correctly aligning them to their desired positions, with the longitudinal axes of the springs being substantially parallel. Assemblies of Strings of Pocketed Coils
As previously discussed, pocketed coil strings may be readily assembled into mattress or cushion assemblies. An example of the use of such strings is shown in my U.S. Pat. Nos. 4,234,984, entitled "POCKETED SPRING ASSEMBLY" and 4,401,501, entitled "APPARATUS FOR MAKING ASSEMBLIES OF POCKETED SPRINGS" in which strips of pocketed upholstery springs are assembled, one strip at a time, into mattresses and the like. The connections of each such strip to its predecessor are made between the interpocket webs of the pocket sheeting of the two adjacent strips, preferably at intervals of two springs, and are staggered by one spring from strip to strip. The disclosed and preferred technique for joining the pocket material of the adjacent strips is thermally welding by ultrasonic vibration, but other specific forms of connection are also suggested.
In my U.S. Pat. No. 4,451,946, entitled "POCKETED SPRING ASSEMBLY", an improvement of my U.S. Pat. No. 4,234,984 is discussed. The improvement includes an elongated connection which connects the pocket sheeting of adjacent strips together between adjacent springs of a strip, with the firmness of the assembly thus being increased by the nature of the elongated interstrip connection.
In my U.S. Pat. No. 4,523,344, entitled "INDEPENDENT BLOCK ASSEMBLY OF SPRINGS", a spring assembly is disclosed which includes a plurality of interconnected longitudinal blocks of pocketed coil springs. each block includes a pair of interconnected strips of pocketed springs which are preferably arranged in a square array. Each pair of strips is tightly encased by a flexible cover. The covers are connected to each other along longitudinal hinge lines which allows the assembly to bend easily in at least one direction.
In my U.S. Pat. No. 4,578,834, entitled "INNERSPRING CONSTRUCTION", an innerspring construction including adhered strings of pocketed coil springs is disclosed together with a method of manufacture. The strings are connected to each other by an adhesive applied between the lines of tangency of adjacent coil springs. A hot melt adhesive applicator transverses a string of pocketed coils, depositing a precise amount of adhesive on each coil jacket. A second string is positioned on the first, and pressure is applied thereto. The applicator then traverses the second string in the same manner as the first. The sequence is repeated until an innerspring construction of desired size is created. My U.S. Pat. No. 4,566,926, entitled "METHOD AND APPARATUS FOR MANUFACTURING INNERSPRING CONSTRUCTIONS", a continuation in part of U.S. Pat. No. 4,578,834, discloses the method and apparatus for manufacturing the mattress assembly disclosed in U.S. Pat. No. 4,578,834.
In U.S. Pat. No. 4,485,506, in which I was a co-inventor, entitled "COIL SPRING CONSTRUCTION", a coil spring construction is provided for incorporation within a mattress or a cushion. The construction includes a plurality of independently mounted pocketed coil springs. Resilient stabilizers are provided between the springs to maintain their axial positions. The spring pockets are formed by the sealing of first and second sheets to each other in a substantially circular configuration about the longitudinal axis of the spring. Spring height is determined by the inside diameter of the seal. It should be noted that this disclosure notes that one advantage of this method is that the springs may simply be allowed to expand after insertion and do not require turning. As previously discussed, in methods where compressed springs are inserted into folded strips which are then stitched or welded in a rectangular pattern, the springs must be turned after insertion so that their axes are substantially colinear with the longitudinal axes of the resulting pockets. (col. 2, lines 49-60).
Individual Bellowed Coil Constructions
It has also been known to provide coils which, instead of being configured in the previously-discussed coiled configuration, are constructed in a bellowed-type manner. One example of such a configuration is shown in U.S. Pat. No. 2,433,012 to Zalicovitz, entitled "RESILIENT CONSTRUCTION FOR USE IN FUTURE" which illustrates the use of individual juxtaposed units 100, 101, 102, etc (See FIG. 26) assembled together to form a box spring assembly, which may be covered by a cloth layer 105 having folds 106, 107, etc., extending down between the units (see col 6, lines 35-42). The individual units may be composed of a resilient material such as metal, paper, cardboard, or synthetic plastics.
U.S. Pat. No. 3,251,077 to Beckman entitled "SPRING ASSEMBLY" discloses the use of individual bellows-type springs 14 which are intermeshed as shown in FIG. 4, such that an upright bellows intermeshes with adjacently-positioned inverted bellows, providing interaction of the individual bellows.
U.S. Pat No. 3,263,247 to Knittel, et. al., entitled "HEADED HOLLOW BODY SUPPORT" discloses the use of molded spring units 16 each including a head 30 and a plurality of bellows 18. As shown in Figure 2, the spring units may be arranged together without bellows interaction with the heads in side-abutting relationship, or may be arranged as shown in FIG. 4 such that upright and inverted spring units are adjacently positioned and the spring bellows interact.
U.S. Pat. No. 3,638,254 to Falkenau, entitled "SPRING", discloses an individual spring unit 10 which may be positioned alongside similarly-shaped springs to provide a mattress foundation shown in FIGS. 4 and 6. The springs may be made of a "suitable plastic material, preferably polypropylene, or, for example, polyvinyl chloride" (see Col. 2, lines 40-41). As shown in FIG. 7, a cover may be provided over the springs and attached to the frame (see col. 2, lines 54-55).
U.S. Pat. No. 3,815,887 to Curtis, entitled "PLASTIC SPRING", illustrates a particular thin wall, hollow, corrugated spring provided with a plurality of annular peaks, each separated by a respective one of a plurality of annular valleys. Column 1, lines 42-44 indicates that the spring could be used in a sofa construction.
Disadvantages in the Prior Art
Although the above-discussed patents provide configurations which include distinct advantages, it should be understood that some shortcomings do also exist. The configurations which require coil springs to undergo severe axial compression during insertion into fabric pockets possess severe disadvantages as they may allow the springs to become tangled or "hooked"on themselves instead of expanding to their desired position. Therefore additional labor is required to "unhook" the springs to allow them to expand as desired.
The configurations which require turning of coil springs after insertion into the pockets also possess disadvantages in that the springs may not be accurately positioned during the turning process, thus resulting in the assembly of pocketed coil strings which may have springs which are not axially aligned.
Furthermore, it may be seen that pocketed coil springs, when under compression, exert pressure at their axial ends at a relatively concentrated area, that being at the "hoop" at which the coils terminate. It should be understood that this concentrated point of contact results in disadvantages failure at the point at which the coil hoop contacts the surrounding fabric pocket. After failure, the coil may escape from the pocket, not only losing its effectiveness but also presenting possible discomfort to the user.
The configurations illustrating the use of bellows-type springs, although providing advantages, are nevertheless required to be individually placed within a mattress or cushion construction, requiring excessive labor expenditures.
Therefore, it may be seen that a need exists for a spring array which overcomes the disadvantages in the prior art by eliminating any requirements for fabric pockets. Furthermore, it may be seen that a need exists for a spring used within such arrays with increased load bearing surfaces at its axial ends, to reduce the tendency of failure between the coils and the surfaces upon which they bear. Finally, a need has always existed to provide mattress materials which are cost-and-labor effective in that they require a minimum amount of materials and labor.